Remove dead content sniffing code

Source/core/loader/DocumentLoader.cpp

 /*
  * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 718 matching lines @@
 
     // willSendRequest() may lead to our LocalFrame being detached or cancelling the load via nulling the ResourceRequest.
     if (!m_frame || m_request.isNull())
         return;
 
     m_applicationCacheHost->willStartLoadingMainResource(m_request);
     prepareSubframeArchiveLoadIfNeeded();
 
     ResourceRequest request(m_request);
     DEFINE_STATIC_LOCAL(ResourceLoaderOptions, mainResourceLoadOptions,
-        (SniffContent, DoNotBufferData, AllowStoredCredentials, ClientRequestedCredentials, CheckContentSecurityPolicy, DocumentContext));
+        (DoNotBufferData, AllowStoredCredentials, ClientRequestedCredentials, CheckContentSecurityPolicy, DocumentContext));
     FetchRequest cachedResourceRequest(request, FetchInitiatorTypeNames::document, mainResourceLoadOptions);
     m_mainResource = m_fetcher->fetchMainResource(cachedResourceRequest, m_substituteData);
     if (!m_mainResource) {
         m_request = ResourceRequest();
         // If the load was aborted by clearing m_request, it's possible the ApplicationCacheHost
         // is now in a state where starting an empty load will be inconsistent. Replace it with
         // a new ApplicationCacheHost.
         m_applicationCacheHost = adoptPtr(new ApplicationCacheHost(this));
         maybeLoadEmpty();
         return;
@@ skipping 73 matching lines @@
 // This is only called by FrameLoader::replaceDocumentWhileExecutingJavaScriptURL()
 void DocumentLoader::replaceDocumentWhileExecutingJavaScriptURL(const DocumentInit& init, const String& source, Document* ownerDocument)
 {
     m_writer = createWriterFor(ownerDocument, init, mimeType(), m_writer ? m_writer->encoding() : emptyAtom, true);
     if (!source.isNull())
         m_writer->appendReplacingData(source);
     endWriting(m_writer.get());
 }
 
 } // namespace blink